Hydraulic drive systems for mineral mining machines



July 16, 1968 F. s. ANDERSON 3,392,525

Filed Nov. 1, 1966 HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES 4Sheets-Sheet 1 FIG. I

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HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES Filed Nov. 1, 1966 4Sheets-Sheet 2 y 16, 1963 F. s. ANDERSON I 3,392,525

HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES 4 Sheets-Sheet 3Filed Nov.

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HYDRAULIC DRIVE SYSTEMS FOR MINERAL MINING MACHINES Filed Nov. 1, 1966 4Sheets-Sheet 4 United States Patent "ice 3,392,525 HYDRAULIC DRIVESYSTEMS FOR MINERAL MINING MACHINES Forrest S. Anderson, Carluke,Scotland, assignor to Anderson Mavor Limited, Motherwell, Larnarlrshire,Scotland, a corporation of the United Kingdom of Great Britain andNorthern Ireland Filed Nov. 1, 1966, Ser. No. 591,164 Claims priority,application Great Britain, Nov. 2, 1965, 46,316/65 13 Claims. (CI.60-52) This invention is concerned with fluid pressure drive systems formineral mining machines of the type which are operatively hauled by theaction of chain or rope means, or the like.

According to known practice working fluid is pumped through afluid-conducting circuit containing a fluid-pressure motor which servesas the means by which haulage of the machine along the conveyor isoperatively powered. The fluid discharged from the motor is eitherreturned to a reservoir from which the working fluid is pumped, or backto the pump. In the former case the circuit is of the type known as anopen hydraulic circuit while in the latter case the circuit is of thetype known as a closed hydraulic circuit. In the case of a closedhydraulic circuit it has hitherto been known to incorporate a primingpump which is used operatively to pump working fluid from a reservoirthereof through valve means to the suction of the first-mentioned pump,hereinafter referred to as the main pump, to compensate for any fluidleakage in the closed circuit, the excess of working fluid pumped by thepriming pump being returned through further valve means to thereservoir.

In both open and closed hydraulic circuits a manually operable controlvalve is interpolated in the fluid flow and return lines to and from,respectively, the hydraulic motor, each of the portions of the two fluidlines between the control valve and the hydraulic motor being a portionof the fluid flow line or a portion of the fluid return line dependingon the operative setting of the control valve. Thus when the controlvalve is in one operative setting one of said portions is a portion ofthe fluid flow line and the other of said portions is a portion of thefluid return line while, when the control valve is in another operativesetting, said one of said portions is a portion of the fluid return lineand said other of said portions is a portion of the fluid flow line. Thedirection of rotation of the hydraulic motor, and hence the direction oftravel of the machine along the conveyor, is therefore dependent on theoperative setting of the control valve. The control valve is alsoprovided with an oif setting in which both said portions of the twofluid lines between the control valve and the hydraulic motor are closedat the control valve, working fluid from the delivery of the main pumpbeing by-passed through the control valve directly from the portion ofthe fluid flow line on the pump side of the control valve to the portionof the fluid return line on the reservoir side of the control valve ifthe circuit is an open hydraulic circuit, or to the portion of the fluidreturn line On the main pump side of the control valve if the circuit isa closed hydraulic circuit.

With reference to an open hydraulic circuit, the main pump, and withreference to a closed hydraulic circuit, the main and priming pumps areoperatively driven by power means such as an electric motor coupled tothe pump or pumps, usually through gearing. It is, however, adisadvantage of the known constructions that said power means may stop,or be deliberately stopped, with the control valve in an operativesetting i.e. in other than the off setting.

The primary object of the present invention is to pro- 3,392,525Patented July 16, 1968 vide a hydraulic drive system of either of thetypes described in which, should the power means stop, or be stopped,with the control valve in an operative setting the control valve isautomatically moved to the off setting.

A fluid pressure drive system according to the invention includes apumping means, a power means coupled to the pumping means, a fluidpressure motor, a fluidconducting circuit by which the pumping means andthe fluid pressure motor are connected to one another, a control valvehaving at least one operative position and an off" position intercalatedin the fluid-conducting circuit, and a thrusting device incorporating amovable member movable between two extreme positions, one of which is anoperative position in which it is engageable with the control valvemechanism to operate said mechanism to cause the control valve to moveto the off position if it is not already in that position and aninoperative position in which it is out of engagement with the controlvalve mechanism, the movable member being connected into thefluid-conducting circuit in such wise that any pressure communicated tothe thrusting device from the fluid-conducting circuit tends to move themovable member in the opposite direction to that to which it is biased,the thrusting device being so arranged that as a result of theparticular pressure conditions existing in the fluidconducting circuitduring operation of the pump the movable member is in the inoperativeposition, and when said pressure conditions change as a result ofstoppage of the pump the movable member is moved to the operativeposition.

The pumping means may consist of a single pump or may consist of a mainpump and a priming pump discharging to the main pump. Where a singlepump is used the fluid-conducting circuit may be an open circuit inwhich the exhaust from the fluid-pressure motor is discharged through areturn line to a reservoir and the pump draws operating liquid from thereservoir and supplies it under pressure to the fluid-pressure motor.The return line preferably contains a check valve for maintaining apressure sufliciently above atmospheric in the return line to causeoperation of the thrusting device. Where the pumping means consists of amain pump and a priming pump the fluid-conducting circuit may be aclosed circuit, the exhaust from the fluid-pressure motor beingconducted directly by a return line to the suction of the main pump, thepriming pump being mainly for the purpose of supplying make-up liquid.

The thrusting device may consist of a cylinder in which a piston ismovable, one side of the cylinder having an inlet port connected intothe fluid-conducting circuit and an exhaust port open to discharge byway of a bleed valve and the other side of the piston being engaged by acompression spring urging the piston to move in the direction to reducethe volume of the portion of the cylinder connected to thefluid-conducting circuit, the piston being connected to a piston rodengageable with mechanism associated with the control valve.

Where the pumping means consists of a single pump the inlet port of thethrusting device is connected into the return line of thefluid-conducting circuit. This is because if the inlet port of thethrusting means were connected into the delivery line there would be acontinual loss of pressure in the delivery line through the bleed valve.Where the pumping means consist of a main pump and a priming pump theinlet port of the thrusting means is preferably connected into thedelivery line of the primmg pump.

Where the control valve is operated by a lever the piston rod of thethrusting means may be engageable with the lever so that when the pistonis moved to the end of its stroke corresponding with the operativeposition of the thrusting device the piston rod is engagea'ble with thelever to move the control valve to its off position.

In one construction the control valve is a spring-loaded valvespring-urged to move to the ofF position, the valve being held in anoperative position for either forward or reverse movement of thefluid-pressure motor by a detent engaging a notch or a selected notch inan appropriate movable part of the mechanism for operating the controlvalve. In this construction the piston rod of the thrusting device isoperable when the piston of the thrusting device moves to the operativeposition to withdraw the detent from the notch so that the spring meansof the control valve is operable to move the control valve to the offposition.

Where the inlet port of the thrusting means is connected to the deliveryline of the fluid-conducting circuit the thrusting device may be soarranged that the piston is urged towards the operative position by thespring means, any pressure prevailing in the fluid-conducting circuitacting on the piston to oppose the thrust of the spring and tend to movethe piston to the inoperative position.

Where it is desired that the thrusting device should be operated by thedelivery pressure of the pump the thrusting device may be so arrangedthat the spring urges the piston to move to the inoperative position,fluid pressure acting on the other side of the piston opposing thespring thrust and tending to move the piston to the operative position.In this construction the inlet port of the thrusting device is connectedto the delivery line of the fluid-conducting circuit by way of a valvethe operative member of which is coupled to a piston exposed to thepressure in the return line of the fluid-conducting circuit, thearrangement being such that any pressure in the return line causes thepiston to move to the position to hold the valve closed and preventfluid under pressure from passing from the delivery line to thethrusting means. The return line may incorporate a bleed valveby-passing the check valve.

Practical embodiments of the invention are illustrated diagrammaticallyin the accompanying drawings in which FIGS. 1 and 2 show constructionsincorporating closed fluid-conducting circuits and FIGS. 3 and 4 showconstructions incorporating open fluid-conducting circuits.

In the drawings, 1 denotes a main pump which in the embodiments of FIGS.3 and 4 is the only pump coupled to power means 2 consisting of anelectric motor and 3 (FIGS. 1 and 2), denotes a priming pump. Numerals 4and 5 denote delivery and return lines respectively associated with thepump 1. Numeral 6 (FIGS. 1 and 2) delivery line of the priming pump 3.Numeral 7 denotes fluid lines connected between a fluid pressure motor 8and a control valve 9 to which latter the delivery and return lines 4and 5 are connected. In the embodiments of FIGS. 1 and 2 the lines 4, 5,6, and 7 form the fluid-conducting circuit and in the embodiments ofFIGS. 3 and 4 the lines 4, 5 and 7 constitute the fluid-conductingcircuit. The control valve 9 is operatively connected to an operatinglever 10 swingable about a fulcrum 11 between a forward and a reverseposition, the central position being the otf position. The thrustingmeans consists of a cylinder 12 within which the piston 13 is slidable,a compression spring 14 engaging one side of the piston 13 and urging itto move to the opposite end of the cylinder which latter is formed withan inlet port 15 and an exhaust port 16. In the embodiments of FIGS. 1and 2 the inlet port 15 is connected by way of a line 17 to the deliveryline 6 of the priming pump 3. In the embodiment illustrated in FIG. 3the inlet port 15 of the thrusting means is connected by a line 18 tothe return line 5 of the pump 1, the return line 5 incorporating a checkvalve 19 and discharging to a reservoir 20. In the embodimentillustrated in FIG. 4 the inlet port of the thrusting means is connectedby a line 21 to the delivery line 4 of the pump 1 by way of a valve 22the movable member of which is coupled by a rocker 24 to a controlpiston 25 movable in a cylinder 26 connected by a line 2-7 to thedelivery line 5 of the pump 1. The delivery line 5 incorporates a checkvalve 19 and a bleed valve 28, the check valve 19 and the bleed valve 28being connected in parallel with one another, the delivery line 5discharging to a reservoir 20. The exhaust port 16 of the thrustingmeans is connected to a discharge line 29 in which a bleed valve 33 isintercalated. In the constructions of FIGS. 1, 3 and 4 the piston 13 ofthe thrusting means is connected to a bifurcated abutment member 31 thelimbs of which are engageable with the lever 10 on opposite sides of thefulcrum 11 so that engagement of the abutment member 31 with the levercauses the lever to return to the off position irrespective of theposition it previously occupied i.c. where it was set for forward orreverse motion of the fluid-pressure motor 8. In the construction ofFIG. 2 the control valve 9 is so arranged that spring means 32 urges thevalve 9 to move to the off position, the lever 10 in this constructionbeing formed with notches 33 and 34 engageable by a detent 35 carried bya rocker 36 mounted on a pivot 37, the end of the rocker 36 remote fromthat carrying the detent 35 being engageable by the piston 13. Element38 denotes an overload by-pass valve provided to relieve the pressure inthe delivery line 4 if the fluid-pressure motor 8 should stall.

In practice, and referring first to FIG. 1, the fluidpressure motor 8 issupplied normally with operating fluid by the main pump 1 by way of thedelivery line 4, the control valve 9, the lines 7 and the return line 5,fluid for make-up purposes being supplied by the priming pump 3. All thetime the pumps 1 and 3 are operated the line 6 is under pressure andthis pressure is communicated by way of the line 17 to the cylinder 12and, acting on the piston 13, holds the piston 13 against the thrust ofthe spring 14 at the end of the cylinder such that the bifurcatedabutment 31 is withdrawn from the lever 10 so that the lever 10 may bemoved to either forward or reverse position. There is a continual bleedof fluid under pressure from the cylinder 12 through the discharge line29 but the bleed valve 30 restricts the amount of fluid escaping andsufiicient pressure is maintained in the cylinder 12 to hold thethrusting means in the inoperative position. If the power means 2 isshut off so that the pumps 1 and 3 cease operating the fluid passingthrough the bleed valve 30 causes the pressure in the cylinder 12 todrop since there is now no pumping action to maintain the pressure inthis cylinder against the leakage through the bleed valve 30. When thepressure in the cylinder 12 drops far enough the spring 14 moves thepiston 13 in the direction to bring the bifurcated abutment member 31against the lever 10 and, since the two limbs of the abutment member 31straddle the pivot 11 the lever 10 is moved to the middle position whichis the off position.

In the construction of FIG. 2 the general mode of operation is exactlythe same as that for FIG. 1 except that, since the spring means 32 urgesthe control valve 9 to move to the off position it can only be held inthe forward or reverse position by the engagement of the detent 35 withthe appropriate one of the notches 33, 34. When the pressure from thepriming pump 3 drops consequent on stoppage of the pumps 1 and 3 thepiston 13 moves forward as in the construction of FIG. 1 and the end ofthe piston rod comes against the rocker 36 and swings the detent 35 outof engagement with the notch 33 or 34 with which it was engaged. Thespring means 32 then centralizes the control valve 9 in the otf"position.

In the construction of FIG. 3 the operation is similar to theconstructions of FIGS. 1 and 2 but in this case fluid under pressure issupplied to the cylinder 12 of the thrusting means from the return line5 since if the line 18 were connected to the delivery line 4 there wouldbe a loss of power at the fluid pressure motor 8 because of the constantbleed of fluid under pressure from the delivery line 4 through the bleedvalve 30. As before, if the pump 1 ceases to operate the pressure in thereturn line drops because of leakage of fluid through the bleed valve 30and the thrusting means operates again to bring the bifurcated abutment31 against the lever and centralize the control valve 9 in the offposition.

In the construction of FIG. 4 all the time the pump 1 is operating thedelivery line 4 is under pressure as is also the return line 5. Althoughthe pressure in the line 5 is less than the pressure in the line 4, thepressure in the line 5 acting on the larger area of the piston 25 iseffective to cause the valve 22 to be held closed so that fluid underpressure in the delivery line 4 cannot gain access to the cylinder 12 ofthe thrusting means and the spring 14 acting on the piston 13 of thethrusting means holds the abutment member 31 out of engagement with thelever 10. When the pump 1 ceases operating the pressure in the returnline 5 immediately drops because of leakage of fluid through the bleedvalve 28 into the reservoir but, because of the tension remaining in thehaulage cable the fluid-pressure motor is itself motored for a periodand maintains the pressure in the line 4. Since the pressure in thecylinder 26 has dropped the pressure in the line 4 can now open thevalve 22 so that operating fluid under pressure can gain access to thecylinder 12 of the thrusting means through the inlet port 15 and canmove the piston 13 in opposition to the spring 14 to bring the abutmentmember 31 against the lever 10 to centralize the lever 10 in the offposition. When the machine comes to rest the pressure in the deliveryline 4 drops and also fluid leaks out of the cylinder of the thrustingmeans through the bleed valve 30. The spring 14 thereupon moves thepiston to withdraw the abutment member 31 from engagement with the lever10 thus leaving the lever ready for operation again but remaining in theoff" position until it is operated.

What is claimed is:

1. A fluid pressure drive system including a pumping means, a powermeans coupled to the pumping means, a fluid pressure motor, afluid-conducting circuit by which the pumping means and the fluidpressure motor are connected to one another, a control valve having atleast one operative position and an off position intercalated in thefluid-conducting circuit, and a thrusting device incorporating a movablemember movable between two extreme positions to one of which it isbiased, one of said positions being an operative position in which themovable member is engageable with the control valve mechanism to operatesaid mechanism to cause the control valve to move to the off position ifit is not already in that position and the other being an inoperativeposition in which the movable member is out of engagement with thecontrol valve mechanism, the movable member being connected into thefluid-conducting circuit in such a way that any pressure communicated tothe thrusting device from the fluid-conducting circuit tends to move themovable member in the opposite direction to that to which it is biased,and the thrusting device being so arranged that as a result of theparticular pressure conditions existing in the fluid-conducting circuitduring operation of the pump the movable member is in the inoperativeposition, and when said pressure conditions change as a result ofstoppage of the pump the movable member is moved to the operativeposition.

2. A system as claimed in claim 1 in which the pumping means consists ofa single pump.

3. A system as claimed in claim 1 in which the pumping system consist ofa main pump and a priming pump discharging to the main pump.

4. A system as claimed in claim 2 in which the fluidconducting circuitis an open circuit having a return line through which the exhaust fromthe fluid-pressure motor is discharged and a reservoir is provided toreceive the exhaust from the fluid-pressure motor, the pump beingarranged to draw operating liquid from the reservoir and supply it underpressure to the fluid-pressure motor.

5. A system as claimed in claim 3 in which the fluidconducting circuitis a closed circuit having a return line through which the exhaust fromthe fluid pressure motor is arranged to be conducted directly to thesuction of the main pump, the priming pump being mainly for the purposeof supplying make-up liquid.

6. A system as claimed in claim 1 in which the thrusting device consistsof a cylinder, a piston movable within the cylinder, one end of thecylinder having an inlet port connected into the fluid-conductingcircuit and an exhaust port, a bleed valve through which the exhaustport is open to discharge, a compression spring disposed to urge thepiston to move in the direction to reduce the volume of the portion ofthe cylinder connected to the fluid-conducting circuit, and a piston rodconnected to the piston and operatively engageable with the controlvalve mechamsm.

7. A system as claimed in claim 6 in which the pumping means consists ofa single pump and the inlet port of the cylinder of the thrusting deviceis connected into the return line of the fluid-conducting circuit.

8. A system as claimed in claim 6 in which the pumping means consist ofa main pump and a priming pump and in which the inlet port of thecylinder of the thrusting means is connected into the delivery line ofthe priming pump.

9. A system as claimed in claim 6 in which the control valve mechanismincorporates an operating lever with which the piston rod of thethrusting means is engageable so that when the piston is moved to theend of its stroke corresponding with the Operative position of thethrusting device the piston rod is engageable with the lever to move thecontrol valve to its otf position.

10. A system as claimed in claim 6 in which a spring urges the controlvalve to move to the off position, an appropriate movable part of thevalve mechanism is formed with at least one notch, and a detent isengageable with the notch whereby to hold the valve in an operativeposition against the urge of the spring, the piston rod of the thrustingdevice being arranged to be operable when the piston of the thrustingdevice moves to the operative position to Withdraw the detent from thenotch so that the spring can move the control valve to the off position.

11. A system as claimed in claim 6 in which the inlet port of thethrusting means is connected to the delivery line of thefluid-conducting circuit, the thrusting device being so arranged thatthe piston is urged towards the operative position by the spring, anypressure prevailing in the fluid-conducting circuit acting on the pistonto oppose the thrust of the spring and tend to move the piston to theinoperative position.

12. A system as claimed in claim 6 incorporating a subsidiary valve byway of which the inlet port of the thrusting device is connected to thedelivery line of the fluid-conducting circuit, said subsidiary valvehaving an operative member coupled to a piston exposed to the pressurein the return line of the fluid-conducting circuit, the arrangementbeing such that any pressure in the return line causes the piston tomove to the position to hold the valve closed and prevent fluid underpressure from passing from the delivery line to the thrusting means,which latter is so arranged that the spring urges the piston to move tothe inoperative position, fluid pressure acting on the piston opposingthe spring thrust and tending to move the piston to the operativeposition.

13. A system as claimed in claim 12in which the return line incorporatesa bleed valve.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

1. A FLUID PRESSURE DRIVE SYSTEM INCLUDING A PUMPING MEANS, A POWERMEANS COUPLED TO THE PUMPING MEANS, A FLUID PRESSURE MOTOR, AFLUID-CONDUCTING CIRCUIT BY WHICH THE PUMPING MEANS AND THE FLUIDPRESSURE MOTOR ARE CONNECTED TO ONE ANOTHER, A CONTROL VALVE HAVING ATLEAST ONE OPERATIVE POSITION AND AN "OFF" POSITION INTERCALATED IN THEFLUID-CONDUCTING CIRCUIT, AND A THRUSTING DEVICE INCORPORATING A MOVABLEMEMBER MOVABLE BETWEEN TWO EXTREME POSITIONS TO ONE OF WHICH IT ISBIASED, ONE OF SAID POSITIONS BEING AN OPERATIVE POSITION IN WHICH THEMOVABLE MEMBER IS ENGAGEABLE WITH THE CONTROL VALVE MECHANISM TO OPERATESAID MECHANISM TO A CAUSE THE CONTROL VALVE TO MOVE TO THE "OFF"POSITION IF IT IS NOT ALREADY IN THAT POSITION AND THE OTHER BEING ANINOPERATIVE POSITION IN WHICH THE MOVABLE MEMBER IS OUT OF ENGAGEMENTWITH THE CONTROL VALVE MECHANISM, THE MOVABLE MEMBER BEING CONNECTEDINTO THE FLUID-CONDUCTING CIRCUIT IN SUCH A WAY THAT ANY PRESSURECOMMUNICATED TO THE THRUSTING DEVICE FROM THE FLUID-CONDUCTING CIRCUITTENDS TO MOVE THE MOVABLE MEMBER IN THE OPPOSITE DIRECTION TO THAT TOWHICH IT IS BIASED, AND THE THRUSTING DEVICE BEING SO ARRANGED THAT AS ARESULT OF THE PARTICULAR PRESSURE CONDITIONS EXISTING IN THEFLUID-CONDUCTING CIRCUIT DURING OPERATION OF THE PUMP THE MOVABLE MEMBERIS IN THE INOPERATIVE POSITION, AND WHEN SAID PRESSURE CONDITIONS CHANGEAS A RESULT OF STOPPAGE OF THE PUMP THE MOVABLE MEMBER IS MOVED TO THEOPERATIVE POSITION.